// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/browser/android/java/gin_java_bound_object.h"

#include "base/android/jni_android.h"
#include "base/android/jni_string.h"
#include "base/android/scoped_java_ref.h"
#include "base/strings/utf_string_conversions.h"
#include "content/browser/android/java/jni_helper.h"

using base::android::AttachCurrentThread;
using base::android::ScopedJavaLocalRef;

namespace content {

namespace {

    const char kJavaLangClass[] = "java/lang/Class";
    const char kJavaLangObject[] = "java/lang/Object";
    const char kJavaLangReflectMethod[] = "java/lang/reflect/Method";
    const char kGetClass[] = "getClass";
    const char kGetMethods[] = "getMethods";
    const char kIsAnnotationPresent[] = "isAnnotationPresent";
    const char kReturningJavaLangClass[] = "()Ljava/lang/Class;";
    const char kReturningJavaLangReflectMethodArray[] = "()[Ljava/lang/reflect/Method;";
    const char kTakesJavaLangClassReturningBoolean[] = "(Ljava/lang/Class;)Z";

} // namespace

// static
GinJavaBoundObject* GinJavaBoundObject::CreateNamed(
    const JavaObjectWeakGlobalRef& ref,
    const base::android::JavaRef<jclass>& safe_annotation_clazz)
{
    return new GinJavaBoundObject(ref, safe_annotation_clazz);
}

// static
GinJavaBoundObject* GinJavaBoundObject::CreateTransient(
    const JavaObjectWeakGlobalRef& ref,
    const base::android::JavaRef<jclass>& safe_annotation_clazz,
    int32_t holder)
{
    std::set<int32_t> holders;
    holders.insert(holder);
    return new GinJavaBoundObject(ref, safe_annotation_clazz, holders);
}

GinJavaBoundObject::GinJavaBoundObject(
    const JavaObjectWeakGlobalRef& ref,
    const base::android::JavaRef<jclass>& safe_annotation_clazz)
    : ref_(ref)
    , names_count_(1)
    , object_get_class_method_id_(NULL)
    , are_methods_set_up_(false)
    , safe_annotation_clazz_(safe_annotation_clazz)
{
}

GinJavaBoundObject::GinJavaBoundObject(
    const JavaObjectWeakGlobalRef& ref,
    const base::android::JavaRef<jclass>& safe_annotation_clazz,
    const std::set<int32_t>& holders)
    : ref_(ref)
    , names_count_(0)
    , holders_(holders)
    , object_get_class_method_id_(NULL)
    , are_methods_set_up_(false)
    , safe_annotation_clazz_(safe_annotation_clazz)
{
}

GinJavaBoundObject::~GinJavaBoundObject()
{
}

std::set<std::string> GinJavaBoundObject::GetMethodNames()
{
    EnsureMethodsAreSetUp();
    std::set<std::string> result;
    for (JavaMethodMap::const_iterator it = methods_.begin();
         it != methods_.end();
         ++it) {
        result.insert(it->first);
    }
    return result;
}

bool GinJavaBoundObject::HasMethod(const std::string& method_name)
{
    EnsureMethodsAreSetUp();
    return methods_.find(method_name) != methods_.end();
}

const JavaMethod* GinJavaBoundObject::FindMethod(
    const std::string& method_name,
    size_t num_parameters)
{
    EnsureMethodsAreSetUp();

    // Get all methods with the correct name.
    std::pair<JavaMethodMap::const_iterator, JavaMethodMap::const_iterator>
        iters = methods_.equal_range(method_name);
    if (iters.first == iters.second) {
        return NULL;
    }

    // LIVECONNECT_COMPLIANCE: We just take the first method with the correct
    // number of arguments, while the spec proposes using cost-based algorithm:
    // https://jdk6.java.net/plugin2/liveconnect/#OVERLOADED_METHODS
    for (JavaMethodMap::const_iterator iter = iters.first; iter != iters.second;
         ++iter) {
        if (iter->second->num_parameters() == num_parameters) {
            return iter->second.get();
        }
    }

    return NULL;
}

bool GinJavaBoundObject::IsObjectGetClassMethod(const JavaMethod* method)
{
    EnsureMethodsAreSetUp();
    // As java.lang.Object.getClass is declared to be final, it is sufficient to
    // compare methodIDs.
    return method->id() == object_get_class_method_id_;
}

const base::android::JavaRef<jclass>&
GinJavaBoundObject::GetSafeAnnotationClass()
{
    return safe_annotation_clazz_;
}

base::android::ScopedJavaLocalRef<jclass> GinJavaBoundObject::GetLocalClassRef(
    JNIEnv* env)
{
    if (!object_get_class_method_id_) {
        object_get_class_method_id_ = GetMethodIDFromClassName(
            env, kJavaLangObject, kGetClass, kReturningJavaLangClass);
    }
    ScopedJavaLocalRef<jobject> obj = GetLocalRef(env);
    if (obj.obj()) {
        return base::android::ScopedJavaLocalRef<jclass>(
            env,
            static_cast<jclass>(
                env->CallObjectMethod(obj.obj(), object_get_class_method_id_)));
    } else {
        return base::android::ScopedJavaLocalRef<jclass>();
    }
}

void GinJavaBoundObject::EnsureMethodsAreSetUp()
{
    if (are_methods_set_up_)
        return;
    are_methods_set_up_ = true;

    JNIEnv* env = AttachCurrentThread();

    ScopedJavaLocalRef<jclass> clazz = GetLocalClassRef(env);
    if (clazz.is_null()) {
        return;
    }

    ScopedJavaLocalRef<jobjectArray> methods(env, static_cast<jobjectArray>(env->CallObjectMethod(clazz.obj(), GetMethodIDFromClassName(env, kJavaLangClass, kGetMethods, kReturningJavaLangReflectMethodArray))));

    size_t num_methods = env->GetArrayLength(methods.obj());
    // Java objects always have public methods.
    DCHECK(num_methods);

    for (size_t i = 0; i < num_methods; ++i) {
        ScopedJavaLocalRef<jobject> java_method(
            env,
            env->GetObjectArrayElement(methods.obj(), i));

        if (!safe_annotation_clazz_.is_null()) {
            jboolean safe = env->CallBooleanMethod(java_method.obj(),
                GetMethodIDFromClassName(
                    env,
                    kJavaLangReflectMethod,
                    kIsAnnotationPresent,
                    kTakesJavaLangClassReturningBoolean),
                safe_annotation_clazz_.obj());

            if (!safe)
                continue;
        }

        std::unique_ptr<JavaMethod> method(new JavaMethod(java_method));
        methods_.insert(std::make_pair(method->name(), std::move(method)));
    }
}

} // namespace content
